Improved process for pulping wood



PATENT OFFICE.

JOHN W. DIXON, OF PHILADELPHIA, PENNSYLVANIA.

IIVIPROVED PROCESS FOVR PULPING WOOD.

Specification forming part of Letters Patent No. 55,253, dated June 5,1866.

To all 'whom it may concern;

ABe it known that I, JOHN W. DIXON, of the city of Philadelphia andState of Pennsylvania, have invented a new and useful Improvement in theProcess of Pulping Wood and Woody Matter, applicable also to straw,cane, and other similar vegetable ibrous material and I do herebydeclare the following to be a full and exact description of the same,reference being had to the annexed drawings, which represent three formsof apparatus convenient for applying1 my improved process.

Myimprovement consists in circulating water containing common lime ormagnesia, or a mixture of lime and magnesia in solution, highly heatedand under pressure, continually through the mass of Wood or woody matterto be pulped.

It is also important to force into the woody mass, either before'orafter the treatment with lime or magnesia water, either at intervals orcontinuously. a supply offresh water to replace the gummy or resiuouswater simultaneously forced out by the fresh water forced in.

In applying my process, I prefer the apparatus heretofore described byme, which consists of a strong iron digester, H, capable of sustaining apressure of about two hundred pounds to four hundred pounds per squareinch. It has a man-hole on top and closefittin g cover, an upperperforated diaphragm, C, with a central openin g, D, and a lowerperforated diaphragm E, and central opening, F, and sliding valvecovering the cen trai passage, Gr, for leading off the digested mass ofpulp when produced. The solution of lime or magnesia in the digester isheated by contact with a steam or hot-water coil, introduced at I andpassing out at K.

I is a pump, which continually forces a circulation of the highly-heatedlime or magnesia water, in a liquid state under pressure, from thebottom tothe top of the digester A. At F is a Giifard injector, orfresh-water pump, placed, which forces fresh water into the digesterwhenever desired. v

Q is the exit-pipe for the refuse water filled with gummy and resinousmatter. Itis covered with a weighted or safety-valve, so adjusted as toopen whenever fresh water is forced in.

Instead of the foregoin g, an apparatus shown iu Fig. 2 may be adopted,which consists of a digester, A, similar to that shown in Fig. 1, withits upper and lower diaphragm and heating-coil, Ste., the same as inFig. 1. P is a boiler placed over the fire, or heated otherwise, as maybe most convenient.' This boiler is connected to the digester by twotubestube a, which passes from the boiler up on to the top of thedigester, and tube b, which passes across from the bottom of thedigester to boiler' P.

The effect of this apparatus, the principle of which is well known, isto cause a circulation of the heated lime or magnesia water up the tubea, and across through b, from the bottom of the digester, into theheating-boiler P continually.

Another manner for applying my invent-ionA is shown in Fig. 3, andconsists in employing a digester under pressure, such as digester A,Fig. 3, fitted up exactly as in Fig. l.

From the lower part of the digester a tube, g, passes up above thediaphragm C. A jet of steam is introduced from another boiler at L,below the mouth of this pipe, to force up the water, and thus establisha circulation of highly-heated lime or magnesia water Linder pressure.These plans are mere illustrations of alternative modes of applying myinvention.

The wood or woody matter, straw, Ste., having been fed into either ofthe digesters A or A or A" through the man-hole at the top, and theaperture D D D in the diaphragms C C C" closed up, the pump F, Fig. l,is started, to cause a circulation from bottom to top. In Fig. 2 theheating apparatus itself' causes the circulation, and in Fig. 3 the jetof steam introduced at L causes the circulation. In either a circulationof highly-heated lime or magnesia water under pressure is caused fromthe top down through the mass of woody matter, through diaphragm E E' E,where the water is strained fromthe woody matter, whence the water sostrained is again forced up to the top. This rapid circulation of thehighly-heated lime or magnesia water Linder pressure through the woodymatter enables the highly-heated lime or magnesia water un der pressureto dissolve and carry from the woody matter its gummy, gelatinous, andsilicious matter.

In connection with the foregoing operation fresh water may beintroduced, either by an injector or pump, S, S', or S", to the upperpart of the digesters, either at intervals or continuously, before orafter the lime or magnesia water treatment. The cock Q, Q', or Q" is soloaded in each case as to 4open at intervals, or whenever fresh water isforced into the digester at. S, S', or S". Before the woody matter is tobe Withdrawn, a sufficient quantity of highly-heated water underpressure must be passed through it and drained of, so as to leave nogummy matter in it when the Woody matter is discharged from the digesterby openin g the slide-valves F, F', or F".

I prefer, in operating on Wood, to maintain the lime or magnesia waterat a pressure of one hundred and fty pounds and upward, and thetemperature due thereto, although fair result-s may be obtained withincreased length of time at a somewhat lower pressure-say one hundredand twenty-live pounds.

l do not desire herein to claim any of the forms of apparatus shownabove, as these are merely illustrations of apparatus ,suitable forapplying my invention.

Having thus described my invention, what I claim as new therein isl. Thecirculation of a highly-heated soluv l JOHN W. DIXON. Witnesses:

GEO. BUGKLEY,

BENJ. MGMAKIN, Jr.

